1. Field of the Invention
The present invention relates to medical systems and more particularly to a projection thermographic imaging system including an air-motion resistant thermo-stable enclosure for the patient.
2. Description of the Related Art
In thermographic imaging an image is obtained of a portion of the human body, in the infra-red frequency band, from the heat produced by the body.
It has been recognized that the heat produced at locations on the body surface may differ, depending on the state of the tissue underlying the skin. For example, in breast cancer detection an area of skin of a breast overlying a tumor will frequently produce more heat than the surrounding area. One method of detecting such differential heat areas is direct contact thermography, in which a sheet of luminescent liquid crystal material responds to temperature gradations at the skin by color changes. An alternative, and generally considered more accurate, system, called projection thermography, produces an image of the thermal radiation from a body portion. The image is produced by an optical system (transducer) which converts the infra-red (thermal) radiation to a visible image. The image may be viewed immediately by a physician, on a screen using a thermograph camera, and may be photographed for later study.
The thermograph camera has a phototube sensitive to infrared radiation (heat) and electronic circuitry to convert the infrared image into signals which may be used to produce a visible image. Sometimes the thermograph camera is connected by a cable to a remote CRT monitor which diplays the visible image.
The infrared radiation which is produced by the human body is very faint. Consequently, the thermograph camera must amplify the infrared image it receives many thousands of times. The thermal emission from the human body, because it is so faint and sensitive, may easily be lost in the ambient heat loss and noise due to clothing worn by the patient, air currents, and rapid temperature changes in the examining room. To eliminate interference from clothing, often the patient disrobes, so he or she is naked, during the thermograph examination. In addition, it is important that the room temperature be kept within a narrow range to prevent artifacts which distort and falsify the image. Such disrobing is embarrassing and uncomfortable to many persons, particularly if they must wait in a cool examining room. If the patient wears a robe, his or her body infrared radiation may be distorted by the folds of the robe.
U.S. Pat. No. 4,548,212 entitled "Apparatus For Thermographic Examinations" uses a liquid crystal sheath applied to a portion of the body and which is flooded with a cooling liquid or gas. In one embodiment, a body portion sheath, called an air tent, is applied over the neck and cooling air is blown into the sheath to cool the skin.
A typical and suitable thermograph camera thermal video system is the Model 7300 "Probeye" available from Hughes. It uses a solid state infrared imaging system employing a mercury cadmium tellwide detector having a spectral range of 2.0 to 5.6 microns.